1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a method for reducing the power consumption of an LED (Light-Emitting Diode) driving chip in a standby condition.
2. The Related Arts
Energy saving is a common consensus of all countries in the world and how to reduce standby power consumption of liquid crystal television is now a technical hot spot of a worldwide industry. In the current scenario of major economic crisis, household electrical appliances that save power consumption are getting more popular to the general consumers. In the sector of complete TV set, certain organizations are now working with the manufactures of the complete TV set to bring into practice energy saving certification.
Standby power consumption is referred to the power consumption taken by basic functions of household electrical appliances in a shutoff condition or not put into operation. Contrary to the effective power consumption that is taken when a household electrical appliance is in operation, the standby power consumption is basically a waste of energy. According to international authorities, the standby power consumption of household electrical appliances of the world takes about 3%-13% of civil power consumption and is about 2% of gross power generation. Of the standby power consumption, audio/video devices, such as television, takes a share of about 68.6%. The standby power consumption of television in China is as high as 8.07 W/set.
To conserve the limited electricity resources, European Industrial Alliance (EACEM) stipulates audio products that enter Europe must have a standby power consumption less than 5 W effective as of Jan. 1, 2001, which was lowered to 3 W as of Jan. 1, 2004, and 1 W as of Jan. 1, 2007. China also stipulates that all television sets having a standby power consumption that is greater than 9 W are prohibited from sales as of Mar. 1, 2006 and the energy saving grade is 1 W. In the state of the art, the backlighting of liquid crystal televisions is often an LED light source. A drive chip of an LED light requires three signals, namely VCC, BLON, and PDIM, as shown in FIG. 1, of which VCC stands for input voltage, BLON is an enable signal, and PDIM is a dimmer signal. During use, VCC voltage is constantly present and during standby condition, PDIM voltage is kept in a low level.
However, the state of the art shows a shortcoming of simply overlooking BLON signal being potentially in a high level in the standby condition. Under this condition, most of the functions of the LED driving chip start to operate. This increases power loss of the LED driving chip, which means an increase of standby power consumption.
Thus, it is an issue to be urgently improved by those devoted themselves to the field to provide a driving circuit and method to effectively reduce standby power consumption of a liquid crystal display in order to reduce consumption of an LED driving chip in a standby condition of the liquid crystal display.